That was a 'Market on Close' or MOC trade which is aggregate of all market on close orders.There is one most everyday at close and open. Many trading platform allow this and I do it often. One just needs to set ones MOC order at least 15 minutes before the bell. Same is true for 'Market on Open' or 'MOO' Orders. Any questions call your brokers for clarification. It is a good way to avoid the wipsaws like what happened today near the close. The price is the VWAP of all MOC or MOO orders respectively. SO NO IT WAS NOT A 83K SHARE DUMP